1. Field of the Invention
The present invention relates to semiconductor packages and, more particularly, to a high-power ball grid array (BGA) package having a heat spreader, a method for manufacturing the heat spreader, a BGA printed circuit board (PCB) to which the method is applied, and a method for manufacturing the BGA PCB.
2. Description of the Related Art
As devices become highly integrated, the number of connection pads in a semiconductor device such as a semiconductor memory device increases. Thus, the number of lead lines in a package included in a PCB also increases. As the number of lead lines increases, a lead frame of the conventional package technology cannot be applied to a highly-integrated semiconductor chip having over 400 lead lines. Accordingly, a BGA package has been introduced in which package output terminals are arranged on a large bottom board of the package.
The BGA package includes a square-shaped main body, a semiconductor chip which is mounted on the top surface of the main body, and matrix solder balls at the bottom surface of the main body which contact the printed circuit board and thus can be arranged and mounted on pads of the printed circuit board by using a reflow process.
Such BGA package requires a heat spreader on the surface of the semiconductor chip so as to emit heat to the outside the package when a considerable amount of heat is generated during the operation of the semiconductor chip. However, since a gold wire is formed upwardly to connect the semiconductor chip with the pad of the main body of the package, it is difficult to mount the heat spreader on the BGA package and so such BGA package is not appropriate for a high-power BGA package.
Referring to FIG. 12, there is provided a newly-introduced, high-power BGA package so as to overcome the heat emitting problem of the conventional BGA package. The newly-introduced, high-power BGA package includes a package printed circuit board 1120, a through portion 1200a at the center of the package circuit board 1120, pads for bonding (not shown) at the bottom surface of the printed circuit board 1120, a heat spreader 1110 which is connected to the top surface of the printed circuit board 1120, a supporting main body 1130 which is connected to the bottom surface of the heat spreader 1110, and a semiconductor chip 1101 which is mounted under the supporting main body 1130 within the through portion 1200a, includes a plurality of metal pads 1101a on its bottom surface, and is connected to pads for the bonding (not shown) and gold wires 1101b. Such high-power BGA package is capable of easily emitting heat away and cooling the semiconductor chip through the heat spreader 1110 that is stably mounted on the surface of the BGA package, even though the heat is generated in the semiconductor device.
The heat spreader 1110 of such high-power BGA package, however, is composed of conductive copper and surface-processed nickel, a fact which results in a constant voltage between the semiconductor chip 1101 and the heat spreader 1110 during the operation of the semiconductor chip 1101 and can cause damage to the semiconductor chip 1101 in many cases. The yield of BGA package of the semiconductor device decreases, and the reliability of the semiconductor device may not be ensured when mounting the semiconductor chip on the printed circuit board.